International Appliance Manufacturing 2008 - (Page 14) Key Components of a Wobble Piston Pump Dual Cylinder Design Shown Cylinder Connection Tubes Valves Cylinder Head Gasket Cylinder Gasket Piston Cup Cylinder Cylinder Head Piston and Connecting Rod Vibration Isolating Mounting Cooling Fan Connecting Rod Bearing Motor Bearing Motor Figure 3. Figure 3 described a basic design that survives almost intact to today – with, of course, improvements over the years in materials and manufacturing processes. The patent also contains this precise statement of purpose: “The chief object of the invention is to provide a low cost compressor of high efficiency and long life and requiring a minimum of service. A further object is to produce an efficient long life compressor that requires no lubrication.” How It Works: The key components of a WOB-L piston pump are depicted in Figure 3, above. In the simplest possible terms, a WOB-L pump is mechanically a cross between a diaphragm pump and an articulating piston (or reciprocating piston) pump – the shared mechanical element being an eccentric connecting rod. Applying this design to a piston pump eliminates the need for a connecting wrist pin, which significantly reduces the size, weight and mechanical complexity of the pump. As its name implies, the approach of direct coupling a unitary piston rod to the crank without a wrist pin introduces a characteristic wobbling motion to the piston, as shown in Figure 4, at right. At the bottom of its stroke, the piston is precisely perpendicular to the cylinder wall; as it moves upward, the piston tilts proportional to the ratio of the stroke to the overall rod length, and reaches perfect alignment Figure 4. Composite photo shows the characteristic tilt of a wobble pump’s Composite photo shows the characteristic tilt piston at mid-stroke, at mid-stroke, of a wobble pump’s piston compared with compared with the piston’s perpendicular the piston’s perpendicular orientation at orientation at the top and bottom of the stroke. the top and bottom of the stroke. Figure 4 14 International Appliance Manufacturing 2008
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